<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .box1{
            font: italic bold 20px '微软雅黑';
            border: 1px solid red;
            margin: 10px 10px 20px 20px; /**上、右、下、左*/
            color: #0F0;

            /**
            样式值可以进行简写
            16进制颜色值、0的单位、小数点前面的0均可省略 */
        }

        .common{
            width: 300px;
            height: 300px;
        }

        .box2{
            color: red;
            padding: 10px;
        }

    </style>
</head>
<body>
    <div class="box1,common">
        简化css
    </div>

    <div class="box2,common">
    </div>
    
</body>
</html>